Flow rate ratio variable type fluid supply apparatus

Abstract

A flow rate ratio variable type fluid supply apparatus includes a flow rate control system supplying gas of flow rate q that is diverted to first flow diverting pipe passage and second flow diverting pipe passage with prescribed flow rates q₁/q₀ so gas is supplied to a chamber, and a first orifice having opening area S₁ is installed on the first flow diverting passage, and the second flow diverting passage is connected to a plurality of branch pipe passages connected in parallel, orifices having opening area installed on the branch passages, and open/close valves installed on all, or some of, the branch passages so gas is diverted to flow diverting passages with flow rate ratio q₁/q₀ equivalent to the ratio of the first orifice and the total opening area S₂o of flow passable orifices of the second flow diverting passage by regulating total opening area of the flow passable orifices.

Description

This is a National Phase Application in the United States of International Patent Application No. PCT/JP2007/000629 filed Jun. 13, 2007, which claims priority on Japanese Patent Application No. 2006-177156, filed Jun. 27, 2006. The entire disclosures of the above patent applications are hereby incorporated by reference.

FIELD OF THE INVENTION

The present invention is used for semiconductor manufacturing facilities, and the like, and relates to a flow rate ratio variable type fluid supply apparatus that makes it possible to divert a gas of a set flow rate supplied from a flow rate control system so that it is supplied to a chamber with a desired flow rate ratio.

BACKGROUND OF THE INVENTION

In recent years, there has been a trend seen in that silicon wafers having a larger diameter are used for semiconductor manufacturing. For this reason, when semiconductor manufacturing apparatuses are used, it has become necessary to supply a treatment gas to a chamber through a plurality of supply lines, and to precisely control a flow rate ratio of the gas passing through these supply lines.

FIG. 7 illustrates one example of a gas supply system with which gas is supplied to a chamber through a plurality of supply lines for a conventional semiconductor manufacturing apparatus, wherein flow rate control systems FCS₁, FCS₂ are provided with gas supply lines GL₁, GL₂, respectively, thus allowing regulation of the flow rate ratio γ=Q₁/Q₂ of the supply lines GL₁, GL₂. In FIG. 7, S_T designates a gas supply line, G designates a treatment gas, C designates a chamber, D designates a gas discharger, H designates a wafer, and I designates a wafer holding base. However, with the apparatus as shown in FIG. 7, two flow rate control system units FCS₁, FCS₂ are required, which upsizes the semiconductor manufacturing apparatus and raises costs for equipment and maintenance, thus making it difficult to downsize equipment and to reduce costs.

FIG. 8 shows gas supply equipment previously developed by the inventor of the present invention in order to improve the aforementioned shortcomings of the equipment shown in FIG. 7, wherein gas G is controlled to have a flow rate Q set by the flow rate control system FCS so that gas G is supplied to a chamber C with a desired flow rate ratio γ=Q₁/Q₂ through supply lines GL₁, GL₂, which are provided with pressure type diverted flow rate controllers FV₁, FV₂ controlled by a diverted flow rate control apparatus FRC.

In particular, the gas supply apparatus shown in FIG. 8 is provided with a gas discharger D, which is equipped with orifices OL₁, OL₂ having specific diameters φ₁, φ₂, respectively, installed inside the chamber C. The gas supply apparatus of FIG. 8 is made so that gas of a total quantity Q=Q₁+Q₂ is supplied into the chamber C with desired diverted flow rates Q₁ and Q₂, expressed by Q₁=K₁P₃′ and Q₂=K₂P₃″ (where K₁ and K₂ are constants determined by the cross sectional areas, and the like, of orifices OL₁, OL₂), passing through the orifices OL₁, OL₂, respectively, of the gas discharger D by regulating the gas pressure P₃′, P₃″ on the downstream side by using the diverted flow rate controllers FV₁, FV₂. (Japanese Unexamined Patent Application Publication No. 2004-5308)

However, with the gas supply apparatus shown in FIG. 8, there remains a problem in that the shape, and the like, of the gas discharger D are subsequently restricted because the gas supply apparatus includes that gas discharger D, equipped with orifices OL₁, OL₂ having specified diameters φ₁, φ₂, installed inside the chamber C. Because two flow rate control system units FCS₁, FCS₂ are not needed by the apparatus shown in FIG. 8, compared with the aforementioned gas supply apparatus shown in FIG. 7, costs for equipment, and the like, can be reduced in comparison with the aforementioned gas supply apparatus of FIG. 7. However, it is disadvantageous in that the gas supply apparatus of FIG. 8 requires two diverted flow rate controller units FV₁, FV₂, and also a diverted flow control apparatus FRC. This fact doesn't allow installation costs to be substantially reduced and it doesn't allow drastic downsizing of the diverted gas supply apparatus. In addition, another disadvantage is that it becomes too complicated to control of the flow rate ratio Q₁/Q₂.

Furthermore, FIG. 9 illustrates another system that has been developed previously by the inventors of the present invention to overcome the aforementioned shortcomings of the gas supply system shown in FIG. 8 (Japanese Unexamined Patent Application Publication No. 2004-5308). The gas supply system of FIG. 9 is constituted so that by using simply structured open/close valves V₁, V₂, a pressure type diverted flow rate controller SV, and a flow rate ratio control apparatus CT, the total flow rate Q=Q₁+Q₂ of the gas flow G is supplied into the chamber C with a desired diverted flow rate ratio γ=Q₁/Q₂ in such a manner that the open/close valve of the supply line with a larger flow rate is fully opened and the degree of opening of a pressure type diverted flow rate controller SV is regulated, so as to conduct pressure adjustment of both diverted supply lines GL₁, GL₂ by regulating gas flow rate from a supply line on the larger flow rate side to a supply line on the smaller flow rate side. (Japanese Unexamined Patent Application Publication No. 2005-11258)

However, the same disadvantages with the aforementioned gas supply apparatus shown in FIG. 8 (Japanese Unexamined Patent Application Publication No. 2004-5308) remain unsolved even with the gas supply apparatus of FIG. 9, so it has not been possible to substantially downsize the gas supply apparatus and to reduce equipment costs drastically, and also it has not been possible to freely choose the form of the gas discharger D without limitation.

As shown in FIG. 10, flow rate control systems (Japanese Unexamined Patent Application Publication No. 2003-323217 and others) have been developed as a kind of flow diverting gas supply apparatus, wherein branch supply passages GL₁, GL₂ are equipped with sonic velocity nozzles SN₁, SN₂, respectively, and the pressure P₁ on the upstream side pipe passage from the sonic velocity nozzles SN₁, SN₂ is regulated using an automatic pressure controller ACP, thus allowing gas supply quantities Q₁, Q₂ from the branch supply passages GL₁, GL₂ to be regulated. In FIG. 10, ACQ designates a flow rate control part, and V₁, V₂ designate control valves.

An object of the flow diverting supply apparatus is to simultaneously control gas flow rates Q₁, Q₂ passing through sonic velocity nozzles SN₁, SN₂ (or orifices) in a manner such that the primary side pressure P₁ is regulated using an automatic pressure controller ACP. It is not an immediate object of the invention to regulate the flow rate ratio γ=Q₁/Q₂ of the branch pipe passages GL₁, GL₂ at any given ratio.

• Patent Document 1: Japanese Unexamined Patent Application Publication No. 2004-5308
• Patent Document 2: Japanese Unexamined Patent Application Publication No. 2005-11258
• Patent Document 3: Japanese Unexamined Patent Application Publication No. 2003-323217

OBJECT OF THE INVENTION

The primary object of the present invention is to provide a downsized and low cost flow rate ratio variable type fluid supply apparatus that makes it possible to divert a gas of a prescribed flow rate Q and to supply the diverted gas with a diverted flow rate ratio as desired by using an extremely simply structured open/close valve and orifice. In this way, the present invention solves the aforementioned shortcomings encountered with the conventional apparatus for supplying a diverted gas to a chamber, which include that substantial reduction in size and cost cannot be achieved with the conventional diverted gas supply apparatus because the conventional apparatus requires an automatic pressure controller, an open/close control valve, and a control part thereof, and furthermore, it is found that the accuracy of the conventional apparatus in controlling a diverted flow ratio is low.

SUMMARY OF THE INVENTION

Through the process of developing varied flow rate control apparatuses for which an orifice is employed, the inventors of the present invention have postulated that, under the conditions of critical expansion, an extremely simply structured flow rate ratio variable type fluid supply apparatus can produced by means of adjusting, with high accuracy, the value of a so-called correction coefficient of an orifice to a set value.

The present invention is, therefore, a creation based on the aforementioned idea of the inventors of the present invention. The present invention, in accordance with a first embodiment, is fundamentally constituted so that a flow rate ratio variable type fluid supply apparatus is used to divert a gas of a flow rate Q supplied from a flow rate control system 6 so that the gas flows to a plurality of flow diverting pipe passages 1₁ to 1_n with prescribed flow rates Q₁ to Q_n, respectively. Thus, gas of a flow rate Q is supplied through the flow diverting pipe passages 1₁ to 1_n into a chamber, and orifices 3 . . . having appropriate opening areas S₁ . . . are installed on one or a plurality of flow diverting pipe passages among the aforementioned flow diverting pipe passages 1₁ to 1_n, and the aforementioned remaining flow diverting pipe passages serve as a pipe passage to which a plurality of branch pipe passages 2_a to 2_n are connected in parallel, and orifices 4 . . . having appropriate opening areas S_2O . . . are installed on the aforementioned branch pipe passages 2a to 2n, respectively. Also, open/close valves V_b to V_n are installed on all, or some of, the aforementioned branch pipe passages so that gas of the flow rate Q is diverted so as to flow to diverting pipe passages 1₁ to 1_n with a flow rate ratio of Q₁/Q₂/Q₃ . . . Q_n equivalent to the ratio of the opening area S₁ . . . of orifices 3 on the aforementioned flow diverting pipe passages. By this structure, the total opening area S_2O of flow-passable orifices on the flow diverting pipe passages, provided with branch pipe passages by means of the total opening area S_2O . . . of flow-passable orifices of the remaining flow diverting pipe passages, are regulated by the open/close operation of the open/close valves Vb to Vn.

The present invention, in accordance with a second embodiment, is fundamentally constituted so that the flow rate ratio variable type fluid supply apparatus is used to divert gas of a flow rate Q so that the gas is supplied from the flow rate control system 6 flows to the plurality of flow diverting pipe passages 1₁ to 1_n with prescribed flow rates Q₁ to Q₀, respectively, so that gas of flow rate Q is supplied through flow diverting pipe passages 1₁ to 1_n into the chamber, and wherein orifices 3₁ to 3_n-1 having opening areas S₁ to S_n-1 are installed on the aforementioned flow diverting pipe passage 1₁ to flow diverting pipe passage 1_n-1, and the aforementioned remaining flow diverting pipe passage in is used as the pipe passage to which the plurality of branch pipe passages 2a to 2n are connected in parallel, and orifices 4a to 4n having opening areas S_2a to S_2n are installed on the aforementioned branch pipe passages 2_a to 2_n, respectively. Also, open/close valves V_b to V_n are installed on all, or some of, the aforementioned branch pipe passages so that gas of flow rate Q is diverted and flows to the flow diverting pipe passages 1₁ to 1_n with a flow ratio of Q₁/Q₂/Q₃ . . . Q_n-1/Q₀ that is equivalent to the ratio of opening areas of orifices 3₁ to 3_n-1 on the aforementioned flow diverting pipe passages 1₁ to 1_n and the total opening area S₂₀ of the flow-passable orifice on the flow diverting pipe passage 1_n by regulating the total opening area S₂₀ of flow-passable orifices on the flow diverting pipe passages 1_n using the open/close operation of the open/close valves V_b to V_n.

The present invention, in accordance with a third embodiment, modifies the first embodiment or the second embodiment so that an orifice 3 is constituted with an orifice 3a that has a constant opening area S₁₁ and an orifice 3b that has an opening area S₁₂ that is adjustable and is connected in parallel with orifice 3a.

The present invention, in accordance with a fourth embodiment, is fundamentally constituted so that the flow rate ratio variable type fluid supply apparatus diverts gas of flow rate Q supplied from the flow rate control system 6 so that gas flows to the No. 1 flow diverting pipe passage 1 and the No. 2 flow diverting passage 2 with prescribed flow rates Q₁, Q₀, respectively, so that gas of flow rate Q is supplied through both flow diverting pipe passages 1, 2 into the chamber, wherein the No. 1 orifice 3 has an opening area S₁ and is installed on the aforementioned No. 1 flow diverting pipe passage 1, and also the aforementioned No. 2 flow diverting pipe passage 2 is made to be a pipe passage to which a plurality of branch pipe passages 2a to 2n are connected in parallel, and orifices 4a to 4n having opening areas S₁a to S₂n are installed on the aforementioned branch pipe passages 2a to 2n, respectively, and open/close valves Vb to Vn are installed on all, or some of, the aforementioned branch pipe passages so that gas of flow rate Q is diverted to flow to flow diverting pipe passages 1, 2 with a flow rate ratio Q₁/Q₀ equivalent to the ratio of the opening area of the No. 1 orifice 3 of the aforementioned No. 1 flow diverting pipe passage 1 and the total opening area S₂₀ of the flow-passable orifices of the aforementioned No. 2 flow diverting pipe passage 2 by means of regulating the total opening area S₂₀ of flow-passable orifices of the No. 2 flow diverting pipe passage 2 by the open/close operation of the open/close valves Vb to Vn.

The present invention, in accordance with a fifth embodiment, further modifies the fourth embodiment so that the No. 1 orifice 3, having an opening area S₁, is constituted with an orifice 3a having a constant opening area S₁₁ and an orifice 3b having an opening area S₁₂ that is made to be adjustable and that is connected in parallel with the orifice 3a so that the No. 1 orifice 3 is formed.

The present invention, in accordance with a sixth embodiment, modifies the fourth embodiment so that the No. 2 flow diverting pipe passage 2 is formed by a plurality of branch pipe passages 2a to 2n, and the opening area S₂a of the orifice 4a of the branch pipe passage 2a and the aforementioned opening area S₁ of the No. 1 orifice 3 of the No. 1 flow diverting pipe passage 1 are made to be identical, and the branch pipe passage 2a is connected to the No. 2 branch pipe passage without installing an open/close valve therebetween.

The present invention, in accordance with a seventh embodiment, further modifies the fourth embodiment so that the No. 2 flow diverting pipe passage 2 is formed by four branch pipe passages 2a to 2d, wherein the opening area S₂a of the orifice 4a of the branch pipe passage 2a and the opening area S₁ of the No. 1 orifice 3 of the No. 1 branch pipe passage are made to be identical, and also the opening areas S₂b to S₄d of the orifices 4b to 4d of the remaining branch pipe passages 2b to 2d are made to be 5%, 10% and 20%, respectively, of the opening area S₁ of the No. 1 orifice 3 of the aforementioned No. 1 branch pipe passage, and the remaining branch pipe passages 2b to 2d are provided with open/close valves Vb to Vd, respectively.

The present invention, in accordance with an eighth embodiment, further modifies the fourth embodiment so that the open/close valves Vd to Vn are the only ones with which branch pipe passages 2d to 2n can be either fully opened or fully closed.

The present invention, in accordance with a ninth embodiment, further modifies the fourth embodiment so that the opening areas of orifices 3, and 4a to 4n can be set at appropriate values selecting the correction coefficient depending on the orifice shape and pressure conditions on the upstream side from the orifices.

The present invention, in accordance with a tenth embodiment, further modifies the ninth embodiment so that the correction coefficient is 0.6 or 0.7 depending on how the shape of a diameter φ of the orifices 3, and 4a to 4n has been processed.

The present invention, in accordance with an eleventh embodiment, further modifies the fourth embodiment so that a gap between a diaphragm valve body and a valve seat of a metal diaphragm is used as the No. 1 orifice 3 and the No. 2 orifices 4a to 4n.

The present invention, in accordance with a twelfth embodiment, further modifies the first embodiment, the second embodiment, or the fourth embodiment, so that either the orifice 3 and the orifice 4, or the No. 1 orifice 3 and the No. 2 orifices 4a to 4n, are made to be 2-step cutting type orifices having 2 different orifices OL₁, OL₂, and gas is made to flow from an orifice having a smaller diameter to an orifice having a larger diameter.

EFFECT OF THE INVENTION

Due to the fact that a flow rate ratio variable type fluid supply apparatus of the present invention comprises orifices having prescribed diameters φ and extremely simple-structured open/close valves Vb to Vn, with which pipe passages can be fully opened or fully closed, it is possible to simplify the structure of the fluid supply apparatus; thus, substantial reduction in size and cost can be achieved.

In accordance with the present invention, the flow rate ratio γ can be changed to a plurality of steps at ease by means of switching open/close valves Vb to Vn appropriately, and the flow diverting ratio γ can also be changed to a plurality of steps at ease by means of changing the orifices themselves. In addition, substantial changes of the flow rate ratio γ can be easily achieved by changing the orifices themselves.

Furthermore, in accordance with the present invention, the correction coefficient can be strictly controlled, and the correction coefficient is made to be 0.7 for an orifice having a diameter φ of 0.3 mm or more, and 0.6 for an orifice having a diameter φ of 0.3 mm or less, depending on the shape of processing. Hence, the flow rate ratio variable type fluid supply apparatus, in accordance with the present invention, can reduce the error of the flow diverting ratio Q₁, Q₂ to less than 1% S.P.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of an embodiment of a flow rate ratio variable type fluid supply apparatus in accordance with the present invention.

FIG. 2 is a cross sectional view of a 1-step cutting type orifice.

FIG. 3 is across sectional view of a 2-step cutting type orifice.

FIG. 4 is a block diagram of a test device for testing flow rate characteristics of an orifice.

FIGS. 5a and 5b show flow rate characteristics of orifices of diameter φ=0.1 mm and φ=0.55 mm, respectively, and computation values of the corresponding correction coefficient of these orifices.

FIG. 6 shows the relationship between pressure P₁ on the upstream side from an orifice and the flow rate measuring error (rdg error) in the case when pressure P₂ on the downstream side from an orifice OF is made to be 20 Torr.

FIG. 7 is an explanatory drawing of a conventional gas supply apparatus for a chamber that employs a plurality of lines.

FIG. 8 is another explanatory drawing of another conventional gas supply apparatus for a chamber that employs a plurality of lines.

FIG. 9 is yet another explanatory drawing of yet another conventional gas supply apparatus for a chamber that employs a plurality of lines.

FIG. 10 is an explanatory drawing showing one example of a conventional flow diverting gas supply apparatus that employs a sonic velocity nozzle.

FIG. 11 is a block diagram of another embodiment of a flow rate ratio variable type fluid supply apparatus in accordance with the present invention.

FIG. 12 is a block diagram of another embodiment of a flow rate ratio variable type fluid supply apparatus in accordance with the present invention.

REFERENCE CHARACTERS AND NUMERALS

• • A Flow rate ratio variable type fluid supply apparatus
  • G Gas
  • Q Total flow rate
  • Q₁ to Q_n Flow rate of the No. 1 flow diverting pipe passages
  • Q₀ Flow rate of the No. 2 flow diverting pipe passage
  • Q_a to Q_d Flow rates of diverting or branch pipe passages
  • γ Flow rate ratio (Q₁/Q₀)
  • OF Orifice member
  • OL, OL₁, OL₂ Orifices
  • 1 No. 1 flow diverting pipe passages
  • 2 No. 2 flow diverting pipe passage
  • 2a to 2d Branch pipe passages
  • 3 No. 1 orifices
  • 4 No. 2 orifices
  • S_T Cross sectional area of the total orifice openings
  • S₁ to S_n Opening area of No. 1 orifices
  • S₂a to S₂d Opening area of Branch pipe passage orifices
  • S₂o Total opening area of flow-passable orifices of the No. 2 flow diverting pipe passage 2
  • φ Orifice diameter
  • Vb to Vd Open/Close valves
  • 5 Gas supply source
  • 6 Flow rate control system
  • 7 Process chamber
  • 8a, 8b N₂ supply sources
  • 9 Mol block
  • 10a, 10b Pressure regulators
  • 11 Vacuum gauge
  • 12 Open/close control valve
  • 13 Vacuum pump
  • P₂ Internal gas pressure of the pipe passage
  • P₃ Internal pressure of the chamber
  • A_1a A source of air
  • PS₁ Pressure detector of the pipe passage GL₁
  • PS₂ Pressure detector of the pipe passage GL₂
  • 14 Outlets

BEST MODE FOR CARRYING OUT THE INVENTION

Preferred embodiments in accordance with the present invention are explained hereinafter with reference to drawings. FIG. 1 is a block diagram of a flow rate ratio variable type fluid supply apparatus in accordance with the present invention. In FIG. 1, A designates the flow rate ratio variable type fluid supply apparatus, Q, Q_a to Q_d and Qo designate flow rates, 1 designates the No. 1 flow diverting pipe passage, 2 designates the No. 2 flow diverting pipe passage, 2a, 2b, 2c, 2d designate branch pipe passages, 3 designates that No. 1 orifice, 4a designates the No. 2 orifice, 4b designates the No. 3 orifice, 4c designates the No. 4 orifice, 4d designates the No. 5 orifice, S₁, and S₂a to S₂d designate cross sectional areas of orifices, Vb, Vc, Vd designate open/close valves, 5 designates a gas supply source, 6 designates a flow rate control system and 7 designates a process chamber.

The aforementioned fluid supply source 5 is a supply source of various kinds of gas to be used for semiconductor manufacturing. In accordance with the present embodiment, a N₂ gas supply source is provided. The flow rate control system 6 regulates the gas flow rate Q supplied to the process chamber 7 at a given flow rate. In accordance with the present embodiment, the apparatus A is made so that N₂ gas of a flow rate Q=1 SLM is supplied with the aid of a pressure type flow rate control system FCS.

In accordance with the present embodiment, a chamber having an internal pressure that is regulated to be 10 Torr is employed as the aforementioned process chamber 7, and N₂ gas of a desired flow rate Q₁ is supplied through the No. 1 flow diverting pipe passage 1 to the center part thereof, and N₂ gas of a flow rate Q₂ is supplied through the No. 2 flow diverting pipe passage 2 to the peripheral part thereof, respectively.

Gas G supplied from the aforementioned gas supply source 5 is regulated to have a flow rate of, for example, Q=1 SLM using the flow rate control system 6, and then the gas is supplied into the process chamber 7 through the No. 1 flow diverting pipe passage 1 and the No. 2 flow diverting pipe passage 2. The flow rate ratio γ=Q₁/Q₀ of gas flow passing through the flow diverting pipe passages 1, 2 is regulated according to the predetermined flow diverting ratio γ=Q₁/Q₀ by means of open/close valves Vb to Vd that are made to be appropriately switched for opening/closing (i.e., full opening or full closing). In accordance with the present embodiment, as mentioned before, N₂ gas of Q=1 SLM is supplied as a quantified amount from the flow rate control system 6. In accordance with the present specification, the terms “flow rate ratio” and “flow diverting ratio” are synonymous terms.

With the present embodiment, as below stated, the aforementioned flow rate ratio γ=Q₁/Q₀ is made so that it can be regulated from 1/1 to 1/1.35 in steps of 5%, thus totaling 8 steps (that is, 1/1, 1/1.05, 1/1.1, 1/1.15, 1/1.20, 1/1.25, 1/1.30, 1/1.35) by means of switching the open/close valves Vc to Vd.

Referring to FIG. 1, the gas flow rate passing through orifices 3, and 4a to 4d is in proportion to the cross sectional area of orifices 3, and 4a to 4d when so-called “expansion conditions” are maintained between pressure P₁ on the upstream side and pressure P₂₁ and P₂₂ on the downstream side from orifices 3, and 4a to 4d. Specifically, under critical expansion conditions, the flow rate ratio of gas passing through the orifices is determined by the ratio of cross sectional areas of the orifices.

Now in accordance with FIG. 1, assuming that cross sectional areas of orifices 3, and 4a to 4d are S₁, S₂a, S₂b, S₂c, S₂d, respectively, the flow rate of the No. 1 flow diverting pipe passage 1 is Q₁, the flow rate of the No. 2 flow diverting pipe passage 2 is Q₀, and the supply flow rate in total is Q, so that the flow diverting ratio γ=Q₁/Q₀ can be expressed by the following equation (1):
γ=Q₁/Q₀=S₁/(S₂a+(S₂b+S₂c+S₂d))  (1)

As stated above, the flow diverting ratio γ is made to be γ=1/1 to 1/1.35 (in 8 steps for every 5%), thus it being needed that the following equations (2) and (3) hold, namely
S₁/S₂a=1/1  (2),
S₂a/S₂b/S₂c/S₂d=100/20/10/5  (3).

Next, computation of the total sum of the cross sectional areas of orifices S₁, and S₂a to S₂d, and of the individual cross sectional areas S₁, and S₂a to S₂d is explained. Now, when the internal pressure of the chamber 7 is made to be 10 Torr, then pressure P₂₁, P₂₂ of the downstream side from the orifice is approximately 20 Torr at the maximum when taking pressure loss of valves Vb to Vd, and the like, into consideration. In order that critical expansion conditions hold, it is required that the total cross sectional area S_T of all orifices is determined so that pressure P₁ on the upstream side from the orifice becomes 40 Torr (i.e., P₁/P₂=more than 2) when valves Vb to Vd are fully opened.

In accordance with the present invention, the total sum S_T of the cross sectional areas of orifices S₁, and S₂b to S₂d is computed using the equations for the orifice CV value, as shown in the below-mentioned equations (4) and (5):
Cv=α×S_T/17  (4),
Cv=Qg/(2019×P₁)×(Gg(273+t))  (5).
In equations (4) and (5), a designates a correction coefficient (i.e, 0.8), S_T designates the total cross sectional area of all orifices (mm²), Qg designates the flow rate (i.e., m³/h=0.06), P₁ designates pressure on the upstream side from an orifice (i.e., MPa abs=0.0053), Gg designates the specific gravity of the gaseous fluid (e.g., 0.97), t designates fluid temperature (i.e., ° C.=21). In accordance with the present embodiment, all computations are performed for the total flow rate Q of the gas is 1 SLM, pressure P₁ on the upstream side from the orifice is 40 Torr, the type of gas used is N₂, and the gas temperature is 21° C.

In accordance with the aforementioned equations (4) and (5), the total sum S_T of the cross sectional opening areas of orifices S₁, and 52a to S₂d becomes S_T=2.01 mm², and with the aforementioned equations (1) to (3), the cross sectional opening areas of orifices S₁, and S₂a to S₂d become S₁=S₂a=0.855 mm², S₂b=0.171 mm², S₂c=0.086 mm², and S₂d=0.043 mm², respectively.

Now, as shown in FIG. 1, for example, when open/close valves Vb to Vd are made or operated to be fully opened, then the flow ratio γ becomes γ=Q₁/Q₀=S₁/(S₂a+S₂b+S₂c+S₂d)=1/1.35. When the open/close valves Vb to Vd are made, or operated, to be fully closed, then the flow ratio γ becomes γ=Q₁/Q₀=S₁/S₂a=1/1. Furthermore, when the open/close valve Vb is made to be opened, and valves Vc and Vd are made to be closed, then the flow ratio γ becomes γ=Q₁/Q₀=S₁/(S₁a+S₂b)=1/1.2, and the flow ratio γ=Q₁/Q₀ is regulated between 1/1 and 1/1.35 in 8 steps for every 5% by means of switching the state of the open/close valves Vb to Vd. In accordance with the embodiment shown in FIG. 1, the apparatus A is made so that gas flow is supplied to the chamber 7 through two flow diverting pipe passages, namely, the No. 1 flow diverting pipe passage 1 and the No. 2 flow diverting pipe passage 2. However, it goes without saying that three or more flow diverting pipe passages can be employed, and one or a plurality of pipe passages among them can be equipped with a plurality of branch pipe passages.

Embodiment 1

It is necessary, in reality, that actually measured values are provided regarding the flow rate characteristics and correction coefficient for an orifice member OF having a small cross sectional area. Therefore, measurements of correction coefficients, and the like, were conducted on two types of orifices OF, as shown in FIG. 2 and FIG. 3, by using the flow rate characteristics testing device shown in FIG. 4. Specifically, in accordance with the present embodiment, an orifice OL is formed by performing 1-step cutting of an orifice member OF having an internal diameter of 0.3 mm or more, as shown in FIG. 2, and an orifice OL is formed by performing 2-step cutting of OL₁, OL₂ in the orifice member OF having an internal diameter of 0.3 mm or less as shown in FIG. 3. Whether to choose 1-step cutting or 2-step cutting is determined appropriately depending on the thickness of the orifice member, accuracy of the processing machine, and the like.

The orifice member OF is formed as a so-called gasket type. The orifice member OF is changeably and hermetically inserted and fixed into an orifice holder (not illustrated) that is inserted into a pipe passage. In accordance with the present embodiment, orifice members as shown in FIG. 2 are employed as orifice members having diameters of 0.3 mm, 0.4 mm and 0.9 mm, and an orifice member as shown in FIG. 3 is employed as an orifice member having a diameter of 0.2 mm.

Flow rate characteristics and correction coefficient of each orifice member OF were actually measured with the testing device as shown in FIG. 4. In particular, as shown in FIG. 4, 8a, 8b designate N₂ supply sources, 9 designates a mol block, 10a,10b designate pressure regulators, OF designates an orifice member, 11 designates a vacuum gauge (100 Torr

Baratron), 12 designates an open/close control valve, and 13 designates a vacuum pump. In this case, the measurement accuracy of the mol block is ±0.2% rdg, the measurement accuracy of the pressure regulators 10a, 10b is ±0.2% F.S. (1 to 40%) and ±0.5% S.P. (40 to 100%).

Pressure P₁ on the upstream side from the orifice member OF was regulated using a pressure regulator 10a, and the gas flow rate passing through the orifice was measured with a mol block 9. Pressure on the downstream side from the orifice member OF was regulated using a downstream side pressure adjustor 10b, thus the dependence of the downstream side pressure P₂ was ascertained.

FIG. 5(a) and FIG. 5(b) show flow rate characteristics of orifice members OF in accordance with the present embodiment. FIG. 5(c) shows the correction coefficient α computed from the data of FIG. 5(a) and FIG. 5(b).

Using the test results of the aforementioned embodiment 1, orifice diameters and correction coefficients of the No. 1 flow diverting pipe passage 1 and branch pipe passages 2a, 2b, 2c, 2d, shown in FIG. 1, are selected by making pressure P₁ on the upstream side from the orifices 64 Torr.

TABLE 1
			Reference characters
Pressure P1 on			and numerals for flow
the upstream side			diverting pipe passage
from orifices	Correction		and branch pipe	Orifice diameter
(Torr)	coefficient	Flow rate ratio	passages in FIG. 1	(mm)
64	0.7	100	1	0.9
	0.6	5	2d	0.2
	0.7	10	2c	0.3
	0.7	20	2b	0.4
	0.7	100	2a	0.9

FIG. 6 shows the relationship between pressure P₂ on the upstream side from an orifice and flow rate measuring accuracy in the case wherein pressure P₂ on the downstream side from the orifice member OF is made to be 20 Torr. When pressure P₂ on the downstream side from an orifice reaches 20 Torr, it is understood, as apparent from FIG. 6, that pressure P₁ on the upstream side from the orifice must be maintained more than 64 Torr in order that the measurement value error (rdg. error) be kept within 1% so as to make the measurement accuracy the same as that when pressure P₂ on the downstream side from the orifice is made to be in a state of vacuum.

Table 2 shows the measurement results obtained from the aforementioned embodiment. It is necessary that the total cross sectional opening area be 1.018 mm² when pressure P₁ on the upstream side from the orifice is 64 Torr, the gas supply flow rate Q is 1 SLM, the gas temperature is 21° C., the coefficient of the gas (i.e., the gas specific gravity) is 0.97 (N₂), and correction coefficient is 1. When the area ratio of the orifices is made to be the same (i.e., S₁/S₂a/S₂b/S₂c/S₂d=100/100/20/10/5) as in FIG. 1, the orifices 3, and 4a to 4d, the flow rate ratio γ, the cross sectional orifice area (correction coefficient 0.6 and 0.7), the computed orifice diameter (mm²) (correction coefficient 0.6 and 0.7), and the selected diameter (mm) of the orifice as measured, are as shown in Table 2.

TABLE 2
		Cross	Cross	Cross
		section	section	section	Orifice	Orifice
Reference		area	area	area	diameter	diameter
characters		(mm2)	(mm2)	(mm2)	(mm)	(mm)	Selected
and	Flow	(Correction	(Correction	(Correction	(Correction	(Correction	orifice
numerals	rate	coefficient:	coefficient:	coefficient:	coefficient:	coefficient:	diameter
for orifice	ratio	1)	0.6)	0.7)	0.6)	0.7)	(mm)
3	100	0.433	0.722	0.619	0.959	0.888	0.9
4b	20	0.087	0.144	0.124	0.429	0.397	0.4
4c	10	0.043	0.072	0.062	0.303	0.281	0.3
4d	5	0.022	0.036	0.031	0.214	0.198	0.2
4a	100	0.433	0.722	0.619	0.959	0.888	0.9

In the case wherein the orifice diameter has been manufactured in actuality to be 0.5 mm, it is desirable that the correction coefficient of 0.6 is chosen for an orifice diameter of 0.25 mm or less, and that the correction coefficient of 0.7 is chosen for an orifice diameter of 0.30 mm or more.

In accordance with the aforementioned embodiment, there are employed two flow diverting pipe passages, namely, the No. 1 flow diverting pipe passage 1 and the No. 2 flow diverting passage 2. However, it goes without saying that more than two flow diverting pipe passages can be employed. In the case wherein a plurality of flow diverting pipe passages are employed, one or more of the flow diverting pipe passages among them are made to be ones equipped with the orifice 3, which has a given opening area S₁, and the remaining flow diverting pipe passages are made to be ones equipped with branch pipe passages 2a to 2d.

Furthermore, in accordance with the aforementioned embodiment, it is possible that when setting the flow rate ratio as 1/1.35, the flow diverting ratio may be selected in 8 steps for every 0.5. However, it goes without saying that the range and switching size of the flow diverting ratio can be set arbitrarily.

In addition, with the present embodiment, it is basically so made that an orifice is employed. However, to replace an orifice, a so-called critical nozzle or a gap between a valve body and a valve seat of a metal touch type diaphragm valve can be also employed.

In accordance the aforementioned embodiment shown in FIG. 1, there is formed the No. 1 orifice 3, having a given opening area S₁, within the one orifice piece. However, it is possible that the No. 1 orifice 3, having a given opening area S₁, (S₁=S₁₁+S₁₂), is formed by means of an orifice 3a having a given opening area S₁₁ and an orifice having an adjustable opening area S₁₂ (e.g. a metal touch type diaphragm valve, and the like) that are connected in parallel. Consequently, this structure is useful because, by making the opening area S₁₂ of one orifice out of two component orifices adjustable, the size of the opening area S₁ of the No. 1 orifice 3 is regulated over a certain range, and then is fixed following adjustment.

FIGS. 11 and 12 are block diagrams of a flow rate ratio variable type fluid supply apparatus in accordance with the present invention. In FIGS. 11 and 12, Q, Q₀, Q₁, and Q_a to Q_d, designate flow rates. 1 designates the No. 1 flow diverting pipe passages, 2a, 2b, 2c, and 2d designate branch pipe passages, 3 designates the No. 1 orifices, 4 designates the No. 2 orifices, S₁ to S_n and S₂a to S₂d designate cross sectional areas of orifices, Va, Vb, Vc, and Vd designate open/close valves, 6 designates a flow rate control system and 7 designates a process chamber.

The present invention can be utilized not only as a flow rate ratio variable type fluid supply apparatus, with which gases are supplied to a chamber used with semiconductor manufacturing facilities, but also as a flow rate ratio variable type fluid supply apparatus for supplying gases to various gas supply equipment.

Claims

1. A flow rate ratio variable type fluid supply apparatus, comprising:

(a) a flow rate control system, wherein the flow rate control system supplies gas of a flow rate q;

(b) a plurality of first flow diverting pipe passages connected to the flow rate control system so that gas of flow rate q is diverted to the plurality of first flow diverting pipe passages, wherein each first flow diverting pipe passage is supplied with a prescribed flow rate of diverted gas so that gas of flow rate q is supplied to a chamber through a plurality of outlets;

(c) at least one first orifice member installed on at least one of the plurality of first flow diverting pipe passages, wherein each first orifice member comprises a first orifice formed therein having a first opening area, and any first flow diverting pipe passages that does not have a first orifice member installed forms a second flow diverting pipe passage to which a plurality of branch pipe passages are connected in parallel, wherein the plurality of outlets consists of the outlets of the plurality of first flow diverting pipe passages and the outlets of the second flow diverting pipe passages so that the gas of flow rate q is supplied to a plurality of positions in the chamber through the plurality of outlets;

(d) a plurality of second orifice members installed on the plurality of branch pipe passages, wherein each second orifice member comprises a second orifice formed therein having a second opening area; and

(e) a plurality of open/close valves installed on all, or some of the plurality of branch pipe passages so that gas of flow rate q is diverted and flows to the plurality of first flow diverting pipe passages with a flow rate ratio for each first flow diverting pipe passage that is equivalent to the ratio of the respective first opening area of the corresponding first orifice member on the corresponding first flow diverting pipe passage and a total opening area of all flow-passable second orifices, wherein the total opening area is the sum of the second opening areas of those second orifice members that are flow-passable, and wherein the flow rate ratio is regulated by an open/close operation of the open/close valves installed on the branch pipe passages.

2. A flow rate ratio variable type fluid supply apparatus according to claim 1, wherein the first orifice formed in the first orifice member comprises a first orifice portion that has a constant opening area connected in parallel with a second orifice portion that has an adjustable opening area.

3. A flow rate ratio variable type fluid supply apparatus according to claim 1, wherein the first orifice and the second orifice are 2-step cutting type orifices having two different orifice portions of different diameter, wherein each 2-step cutting type orifice is arranged so that gas flows from a first step orifice portion of the 2-step cutting type orifice to a second step orifice portion of the 2-step cutting type orifice, and wherein the second step orifice portion has a larger diameter than the first step orifice portion.

4. A flow rate ratio variable type fluid supply apparatus, comprising:

(a) a flow rate control system, wherein the flow rate control system supplies gas of a flow rate q;

(b) a plurality of first flow diverting pipe passages connected to the flow rate control system so that gas of flow rate q is diverted to flow to the plurality of first flow diverting pipe passages, wherein each first flow diverting pipe passage is supplied with a prescribed flow rate of diverted gas so that gas of flow rate q is supplied to a chamber through a plurality of outlets;

(c) a plurality of first orifice members installed on all but one of the plurality of first flow diverting pipe passages, wherein each first orifice member comprises a first orifice having a corresponding first opening area, and the one first flow diverting pipe passage without a first orifice member forms a second flow diverting pipe passage to which a plurality of branch pipe passages are connected in parallel, wherein the plurality of outlets consists of the outlets of the plurality of first flow diverting pipe passages and the outlet of the second flow diverting pipe passage so that the gas of flow rate q is supplied to a plurality of positions in the chamber through the plurality of outlets;

(d) a plurality of second orifice members installed on the plurality of branch pipe passages so that there is a second orifice member installed on each of the plurality of branch pipe passages, and each second orifice member comprises a second orifice having a corresponding second opening area; and

(e) a plurality of open/close valves installed on all, or some of, the plurality of branch pipe passages so that gas of flow rate q is diverted to flow to the plurality of first flow diverting pipe passages with a flow rate ratio equivalent to the ratio of the respective first opening area of the corresponding first orifice member on the corresponding first flow diverting pipe passage and a total opening area of a flow-passable orifices on the one second flow diverting pipe passage, wherein the total opening area of the flow-passable orifices on the second flow diverting pipe passage is regulated by open/close operation of the plurality of open/close valves installed on the plurality of branch pipe passages.

5. A flow rate ratio variable type fluid supply apparatus according to claim 4, wherein the first orifice formed in the first orifice member comprises a first orifice portion that has a constant opening area connected in parallel with a second orifice portion that has an adjustable opening area.

6. A flow rate ratio variable type fluid supply apparatus according to claim 4, wherein the first orifice and the second orifice are 2-step cutting type orifices having two different orifice portions of different diameter, wherein each 2-step cutting type orifice is arranged so that gas flows from a first step orifice portion of the 2-step cutting type orifice to a second step orifice portion of the 2-step cutting type orifice, and wherein the second step orifice portion has a larger diameter than the first step orifice portion.

7. A flow rate ratio variable type fluid supply apparatus, comprising:

(a) a chamber, wherein the chamber is a semiconductor manufacturing chamber, and wherein the chamber has two gas supply locations;

(b) a flow rate control system, wherein the flow rate control system supplies gas of a flow rate q to the chamber, and wherein the two gas supply locations are a first supply location and a second supply location;

(c) a first flow diverting pipe passage and a second flow diverting pipe passage connected to the flow rate control system so that gas of flow rate q is diverted to flow to the first flow diverting pipe passage so that gas of flow rate q₁ flows through the first flow diverting pipe passage and gas of flow rate q₀ flows through the second flow diverting pipe passage, wherein Q=Q₁+q₀, so that gas of flow rate q is supplied by the combined flow of gas through an outlet of the first flow diverting pipe passage and an outlet of the second flow diverting pipe passage, respectively, to the first supply location and the second supply location in the chamber at the gas flow rate q;

(d) a first orifice member installed on the first flow diverting pipe passage, wherein the first orifice member comprises a first orifice having a corresponding first opening area;

(e) a plurality of branch pipe passages connected in parallel to the second flow diverting pipe passage;

(f) a plurality of second orifice members installed on the plurality of branch pipe passages so that each branch pipe passage has a second orifice member installed thereon, wherein each second orifice member comprises a second orifice having a corresponding second opening area; and

(g) a plurality of open/close valves installed on all, or some of the branch pipe passages so that gas of flow rate q is diverted to flow to the first flow diverting pipe passage at the flow rate q₁ and to the second flow diverting pipe passage at the flow rate q₀ with a flow rate ratio q₁/q₀ equivalent to the ratio of the first opening area of the first orifice installed on the first flow diverting pipe passage and a total opening area of flow-passable orifices of the second flow diverting pipe passage, wherein the flow rate ratio q₁/q₀ is regulated by controlling the total opening area of the flow-passable orifices of the second flow diverting pipe passage by open/close operation of the open/close valves installed on the branch pipe passages.

8. A flow rate ratio variable type fluid supply apparatus according to claim 7, wherein the first orifice formed in the first orifice member comprises a first orifice portion that has a constant opening area connected in parallel with a second orifice portion that has an adjustable opening area.

9. A flow rate ratio variable type fluid supply apparatus according to claim 7, wherein the plurality of branch pipe passages includes a first branch pipe passage comprising a third orifice formed therein, wherein the third orifice has a third opening area and the first opening area of the first orifice member of the first flow diverting pipe passage is made to be identical to the third opening area, and the first branch pipe passage is connected to the second flow diverting pipe passage without an open/close valve being installed on the first branch pipe passage.

10. A flow rate ratio variable type fluid supply apparatus according to claim 7, wherein four branch pipe passages are connected in parallel to the second flow diverting pipe passage, wherein the four branch pipe passages include a first branch pipe passage comprising a third orifice formed therein that has a third opening area, a second branch pipe passage comprising a fourth orifice formed therein that has a forth opening area, a third branch pipe passage comprising a fifth orifice formed therein that has a fifth opening area, and a fourth branch pipe passage comprising a sixth orifice formed therein that has a sixth opening area, wherein the third opening area of the third orifice of the first branch pipe passage and the first opening area of the first orifice member of the first flow diverting pipe passage are identical, and the fourth opening area, the fifth opening area, and the sixth opening area of the fourth orifice, the fifth orifice, and the sixth orifice, respectively, of the second branch pipe passage, the third branch passage, and the fourth branch passage, respectively, are made to be 5%, 10% and 20%, respectively, of the first opening area of the first orifice of the first flow diverting pipe passage, and each of the second branch pipe passage, the third branch pipe passage, and the fourth branch pipe passage has an open/close valve installed thereon.

11. A flow rate ratio variable type fluid supply apparatus according to claim 7, wherein the open/close valves are valves having an open/close operation so that the branch pipe passages having an open/close valve installed thereon can be only either fully opened or fully closed.

12. A flow rate ratio variable type fluid supply apparatus according to claim 7, wherein the first opening area of the first orifice, and the second opening area of each second orifice, is set at an appropriate value by selection of a correction coefficient depending on orifice shape and pressure conditions upstream from each orifice, respectively.

13. A flow rate ratio variable type fluid supply apparatus according to claim 12, wherein the correction coefficient is selected to be 0.6 or 0.7 depending on how the shape of a diameter φ of the first orifice and the second orifices are processed.

14. A flow rate ratio variable type fluid supply apparatus according to claim 7, wherein a gap between a diaphragm body and a valve seat of a metal diaphragm serves as the first orifice and as the second orifices.

15. A flow rate ratio variable type fluid supply apparatus according to claim 7, wherein the first orifice and the second orifice are 2-step cutting type orifices having two different orifice portions of different diameter, wherein each 2-step cutting type orifice is arranged so that gas flows from a first step orifice portion of the 2-step cutting type orifice to a second step orifice portion of the 2-step cutting type orifice, and wherein the second step orifice portion has a larger diameter than the first step orifice portion.